From e4fe365994a91e787906cad21eea027fdb9a901e Mon Sep 17 00:00:00 2001
From: nothinglo <99703036@nccu.edu.tw>
Date: Fri, 15 Apr 2016 21:01:11 +0800
Subject: [PATCH] Fix the bug about the direction of Normal.

---
 src/shapes/trianglemesh.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/shapes/trianglemesh.cpp b/src/shapes/trianglemesh.cpp
index a8ca7914..3122cb1e 100644
--- a/src/shapes/trianglemesh.cpp
+++ b/src/shapes/trianglemesh.cpp
@@ -449,7 +449,7 @@ Point Triangle::Sample(float u1, float u2, Normal *Ns) const {
     const Point &p2 = mesh->p[v[1]];
     const Point &p3 = mesh->p[v[2]];
     Point p = b1 * p1 + b2 * p2 + (1.f - b1 - b2) * p3;
-    Normal n = Normal(Cross(p2-p1, p3-p1));
+    Normal n = Normal(Cross(p3-p1, p2-p1));
     *Ns = Normalize(n);
     if (ReverseOrientation) *Ns *= -1.f;
     return p;